I have a Harbor Freight "tag-a-long" trailer I pull behind my motorcycle with my camping gear in it. It would work pretty well for scuba gear as well if your not taking your whole garage. It has a "clamshell" or cartop carrier on it that is lockable. The trailer is approximately 3x4 with a 3ft tongue and is pretty lightweight (150#) empty and has 62 ci storage inside. Mine has 8" wheels on it but you can get 12" if you need a few more inches of clearance. A rack could be added to the tongue to carry a cooler. I am sure but you can probably carry 2 to 3 tanks as well as a dive bag inside. Without the tanks you could get two divebags in it with a some additional space for small items or maybe some clothes/towels, tarp, etc. I think it has a 350# max weight but that may be the load weight and not the gross weight. Obviously it would be more for a day trip or weekend. You’d have to carry your BBQ grill, etc in something else.
I paid $350 for mine a few years ago but I don’t think they are too much more than that now. Maybe $400 or so.